1. Field of Invention
The present invention relates apparatus for the spectroscopic analysis of a sample of material for determining the chemical composition of the sample. A particular application of the apparatus may be to spectroscopic analysis of a zone of the atmosphere, with a view to evaluating atmosphere pollution.
2. Description of Prior Art
Spectroscopic analysis of a sample can be carried out by analysing the absorption spectrum or the Raman spectrum of the sample.
Apparatus for such analysis generally necessitate sampling and the measures carried into effect on the said sample do not make it possible to follow the evolution of the composition of the medium from which the said sample has been taken.
Spectroscopic analysis apparatus are known which do permit the recording of the luminous phenomena emission spectrum making it possible to follow the evolution of such a spectrum, but the field of application of these apparatus is limited solely to highly luminous elements.
Recently developed apparatus utilise extremely high power lasers by means of which the Raman retrodiffusion or back scattering may be studied for analysing the sample. These apparatus are intended to perform the same functions as the apparatus according to the invention but they have the disadvantage that they necessitate extremely large installations and that they are relatively dangerous due to the high power of the laser beam which is used.
It is a characteristic of these apparatus, that analysis of a sample is performed utilising the Raman spectrum.
Analysis apparatus are known which measure the absorption of a medium on an extremely small number of emitted wavelengths. These apparatus, however, do not permit the analysis of complex mixtures and modification of these apparatus in respect of the selection of wavelengths is difficult.